3pi robot: a small, high-performance, autonomous robot designed to excel in line
following and maze solving competitions. Powered by four
AAA batteries (not included) and a unique power system
that runs the motors at a regulated 9.25V, 3pi is capable
of speeds up to 100 cm/second while making precise
turns and spins that don’t vary with the battery voltage.
This results in highly consistent and repeatable performance of well-tuned code even as the batteries run low.

The robot comes fully assembled with two micro metal
gearmotors, five reflectance sensors, an 8x2 character
LCD, a buzzer, three user pushbuttons, and more, all
connected to a user-programmable AVR microcontroller.
The 3pi measures approximately 3. 7 inches ( 9. 5 cm) in
diameter and weighs 2. 9 oz ( 83 g) without batteries.

The 3pi is based on an Atmel ATmega168 microcontroller
running at 20 MHz with 16 KB of Flash program memory
and 1KB data memory. The use of the ATmega168 microcontroller makes the 3pi compatible with the popular Arduino
development platform. Free C and C++ development tools
are also available, and an extensive set of libraries make
it simple to interface with all of the integrated hardware.
Sample programs are available to show how to use the
various 3pi components, as well as how to perform more
complex behaviors such as line following and maze solving.

ICC for Propeller, offered by ImageCraft, is an ANSI C
development tool for the Parallax Propeller chip. The
IDE features project-based design and supports C86 dialect
source and C-based Propeller objects. The Propellent Library

is directly supported by the IDE
for ease in build-to-run development cycles. ICC for Propeller
comes in both a Standard

Version (#32385) and also
a Non-Commercial

Version (#32380).

Both versions feature
an ANSI C compiler for
Propeller LMM code generation with an editor, project
manager, and code browser. The non-commerical version
supports programs as large as 16K while the standard
version supports programs as large as Hub RAM.

The Propeller chip makes it easy to rapidly develop
embedded applications. Its eight processors (cogs) can
operate simultaneously, either independently or cooperatively, sharing common resources through a central hub.
The developer has full control over how and when each
cog is employed; there is no compiler-driven or operating
system-driven splitting of tasks among multiple cogs.
A shared system clock keeps each cog on the same time
reference, allowing for true deterministic timing and
synchronization. Three programming languages are
available: C (via ICC for Propeller), the easy-to-learn
high-level Spin (native), and Propeller Assembly (native)
which can execute at up to 160 MIPS ( 20 MIPS per cog).

ICC for Propeller is available for purchase from
Parallax, Inc.

For further information, please contact:

Parallax, Inc. Website: www.parallax.com

MOTOR CONTROLLER

MDL-STPR77 2.5A Bipolar
Stepper Driver

MDL-STPR77 stands for a
Stepper Driver Module
revolving around Allegro’s A3977
micro-stepping, fully integrated driver.
The module — measuring 2” by 2”
— takes full advantage of the flexibility of the A3977 control signals.
ENABLE, DIR, STEP, RESET, HOME, SLEEP, MS1, MS2 signals,
along with VDD and GND are made available through a
10-pin header for microcontroller interfacing. MS1, MS2,
SR, and SLEEP can be tied to GND or continuedonpage78